1. Field of the Invention
The present invention is directed to a folding stage and in particular, to an elevationally adjustable mobile folding stage.
2. Prior Art
Folding stages are used for a variety of purposes to provide a temporary raised platform for use in schools, hotels, convention centers and other institutions or multiple use facilities requiring the capability of setting up temporary stages. Such stages may be positioned adjacent one another to form an extended stage surface or positioned to support bridging decks between the stages to form an extended stage surface. When not in use, the stages have a framework that folds to compact dimensions and stored along with the bridging decks. The stages typically have two stage decks hinged together to provide for folding action and have legs which remain vertical when the stage decks fold. An example of such a folding stage is shown in U.S. Pat. No. 5,325,640 to Luedke et al., issued Jul. 5, 1994, and assigned to Sico Incorporated, the assignee of the present invention. Although the Luedke et al. patent is very successful in providing efficient and useful folding stages, further improvements are still possible, particularly with regard to stages that fold from the use position to the storage position with the underside of the stages substantially opposing one another in the folded storage position. The support framework and legs of the stage must provide a wide stable base for supporting the stage to prevent wobbling or tipping. It can be appreciated that stability is important both when in a use position, as well as in the folded storage position. Although the Luedke et al. stage provides a stable base, in the storage position when the stage is supported on casters, the distance between the telescoping legs and the casters provides a relatively large moment force about the frame and causes stresses on the caster mounting structure. However, movement of the casters closer to the support legs decreases the width of the support base and the stability of the stage in the folded position.
The folding motion from the folded position to the unfolded position, as well as from the unfolded position to the folded position, should require substantially little effort To accomplish this, the decks and framework should pivot at a substantially center balanced point at the center of gravity so that undue force is not necessary. In addition, unbalance at any point in the range of motion may cause undue folding speed, so that decks may fall into place at either end of the range of motion. This can lead to accidents wherein hands and fingers may be pinched between linkage members or deck members.
In addition, a spacing linkage should provide locking movement and a handle to engage and disengage from a locking position. Such a handle should provide for aiding the folding motion of the stage. Although the Luedke et al. patent has a center lock linkage with a handle, it is in a position wherein hands and arms may be pinched between folding links as they move toward the folded position. This may cause safety concerns and reduced operational efficiency.
It can be seen then that there is a need for a folding stage that provides for a stable base without undue stresses on the casters and support frame in a folded position. In addition, it can be seen that further improvements are possible with regard to folding linkages, balance and torque, and accessibility of spacing linkages and associated handles.